There are a few reasons for that really. They might be attempting to head off some huge hemorrhaging of Alliance to the Horde come TBC. I believe this is also likely why they chose a continuation rather than Fresh TBC. In addition, things that can be pointed at on a spreadsheet really resonate with this dev team. Spreadsheet gameplay, design, and balance is kinda their thing. So things like that are much more likely to get their attention than things that are harder to quantify.
For things that are harder to quantify, it often takes something like a video of something going viral and making them look bad.